This invention relates to wedge-lock type circuit card retainers and more particularly to a combination of wedge-lock type circuit card retainer and a circuit card retainer slot for mounting into an electronic chassis.
Some conventional wedge-lock type circuit card retainers such as those available from Rexnord Inc. of Hasbrouck, N.J. are designed for riveting directly to the circuit card and the circuit card with the assembled retainer fixed thereon are inserted in retainer slot or guide member fastened to the electronic chassis.
These conventional retainers include an elongated shaft-like driver member having a head end provided with a hex, slot or cross type recess for mating engagement with an appropriate tool for manipulation of the driver member. The opposite end of the driver member includes a threaded section onto which an end wedge or cam member is adapted to be threadably mounted. A driver wedge or cam member having an aperture sized to provide a clearance fit for the driver is adapted for mounting on the driver adjacent the head end. A middle wedge or cam member is adapted to be mounted on the driver member intermediate the driver cam member and the end cam member. The middle cam member is provided with a channel which allows free axial and lateral movement of the driver member therein. The middle cam member is adapted to fixed to the circuit card by rivets or screws and is fitted with an alignment leaf spring. The opposite ends of the leaf spring extended beyond the middle cam member and engage with the driver cam member and the end cam member for retaining both of these cam members in alignment with the middle cam member in a fully assembled retainer.
In a fully assembled retainer clockwise rotation of the drive member will drive the camming surfaces of both the driver cam member and the end cam member against corresponding cam surfaces on the fixed middle cam member. Thereby forcing the end and driver cam member in a lateral direction away from the circuit card and into engagement with a retainer slot in the chassis.
In many instances these conventional circuit card retainers function adequately to lock the circuit card to the chassis. In some instances, when multi-layer circuit cards are used, it is desirable to utilize the maximum amount of circuit card surface on the inner layers of the circuit card. However, the need of riveting these circuit card retainers to the circuit board requires the avoidance of routing circuits in the surface area required for riveting. This restriction reduces the amount of board space that is available on each of the internal layers. In circuit card applications requiring high density circuitry such a restriction may require an increase in board size or additional layers, to accommodate the desired circuit routing, thereby increasing costs.
Normally, these conventional wedge-lock retainers are shipped in an unassembled condition, that is, each of the retainer assembly elements are shipped as discrete parts requiring individual handling and the subsequent assembly of the parts after rivet or screw mounting of the retainer to the circuit card.
Along with the foregoing discrete retainer elements conventional electronic chassis circuit card guides are fabricated as a separate part which is subsequently fastened to the chassis. Here again entailing a parts handling expense.
According to the principles of this invention one embodiment provides a combination circuit card retainer and guide slot for use in an electronic chassis that includes an elongated base member having a circuit card guide wall formed along one side. One end of the base member has a fixed wedge formed thereon spaced from and facing the guide wall. A support aligned with the fixed wedge is formed adjacent the other end of the base member and it is also spaced from the guide wall. The circuit card retainer further includes a shaft having a head end and a thread end. The shaft extends through the fixed wedge with the thread end engaged in an aperture formed in the support. An end wedge is mounted on the shaft adjacent the thread end with a center wedge mounted on the shaft between the fixed and end wedges. The center wedge is provided with a spring that is grounded on the base member for biasing the center wedge into engagement and alignment with the fixed and the end wedges. The aligned wedges together with the guide wall forming a circuit card channel or slot. The circuit card retainer is adapted for mounting to a wall of the electronic chassis.
These and other features, advantages and details of the invention can be had from the following description and claims taken together with the accompanying drawing.